TRADITIONAL POSTER - ismrm

Poster Sessions
Diffusion: Pulse Sequences
Hall B Tuesday 13:30-15:30
1610. Isotropic High Resolution Diffusion-Tensor Imaging in Humans at 7T
Robin Martin Heidemann 1 , Alfred Anwander 1 , Thomas Knoesche 1 , Thorsten Feiweier 2 , Fabrizio Fasano 3 ,
Josef Pfeuffer 2 , Robert Turner 1
1 Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany; 2 Siemens Healthcare Sector, Erlangen, Germany;
3 Fondazione Santa Lucia, Rome, Italy
For isotropic high resolution DTI at ultra-high field strength, susceptibility effects and T2* decay must be properly addressed. A combination of reduced
FOV imaging (zoomed imaging) and parallel imaging is optimized here, achieving high acceleration factors. This approach enables DWI acquisitions with 1
mm isotropic resolution at 7T. The high quality of the DTI data provides a high level of anatomical details.
1611. Reduced-FOV Diffusion Imaging with ZOnal Oblique Multislice (ZOOM) Combined with Readout-
Segmented (RS)-EPI
Samantha J. Holdsworth 1 , Stefan Skare 1 , Rafael Luis O'Hallaran 1 , Roland Bammer 1
1 Radiology, Stanford University, Palo Alto, CA, United States
Diffusion-weighted imaging (DWI) using EPI has been limited by geometric distortion and blurring, particularly in regions with large off-resonance effects.
Distortions can be reduced by reducing the phase-encode FOV, and by reducing the echo-spacing. For the former, we implement the ZOnal Oblique
Multislice (ZOOM) technique, which uses a tilted refocusing pulse to spatially select a region of interest. To reduce echo-spacing further, we use the
readout-segmented (RS)-EPI technique. We show that the combination of the ZOOM pulse and RS-EPI results in images of the spine and orbits with
reduced geometric distortion.
1612. Robust Fat Suppression for High-Resolution Diffusion-Weighted Imaging
Joelle E. Sarlls 1,2 , Wen-Ming Luh 3 , Carlo Pierpaoli 1
1 NICHD, National Institutes of Health, Bethesda, MD, United States; 2 Henry M. Jackson Foundation, Rockville, MD, United States;
3 NIMH, National Institutes of Health, Bethesda, MD, United States
Although spectral-spatial excitation pulses provide single-shot EPI diffusion-weighted images without signal from fat, they are limited in the attainable
minimum slice thickness. To achieve higher resolution, traditional fat supression methods must be used. In this work, an exhaustive investigation was
performed to determine which, if any, implementation of the slice-selective gradient reversal method completely supressed the fat signal. The dual-spinecho
diffusion preparation implementation, with opposite polarity slice-select gradients for the two 180° refocusing pulses, combined with traditional fat
supression was found to completely suppress fat in phantoms and in vivo.
1613. Improved Prospective Optical Motion Correction for DTI Using an Extended-Field-Of-View and Self-
Encoded Marker
Murat Aksoy 1 , Christoph Forman 1 , Matus Straka 1 , Samantha Jane Holdsworth 1 , Stefan Tor Skare 1 , Juan
Manuel Santos 2 , Joachim Hornegger 3 , Roland Bammer 1
1 Department of Radiology, Stanford University, Stanford, CA, United States; 2 Electrical Engineering, Stanford University, Stanford,
CA, United States; 3 Computer Science, Friedrich-Alexander-University Erlangen-Nuremberg, Erlangen, Germany
Due to the prolonged acquisition time, correction of rigid-head motion artifacts is essential for diagnostic image quality in diffusion tensor imaging (DTI). In
this study, we performed prospective, real-time rigid head motion correction for DTI. This is achieved by using a single camera mounted on a head coil
together with a 3D, self-encoded checkerboard marker that is attached to the patient's forehead. The results show that the proposed setup is very effective in
removing rigid head motion artifacts even for very motion-sensitive scans, such as DTI.
1614. High Angular Resolution Diffusion Imaging (HARDI) with Highly Constrained Back Projection
Reconstruction (HYPR)
Yu-Chien Wu 1 , Charles A. Mistretta 2 , Andrew L. Alexander 3 , Trevor Andrews 4 , Paul J. Whalen 5 , James V.
Haxby 5
1 Dartmouth Brain Imaging Center, Dartmouth College, Hanover, NH, United States; 2 Wisconsin Institutes for Medical Research,
University of Wisconsin-Madison, Madison, WI, United States; 3 Medical Physics, University of Wisconsin-Madison, Madison, WI,
United States; 4 College of Medicine, University of Vermont, Burlington, VT, United States; 5 Psychological & Brain Sciences,
Dartmouth College, Hanover, NH, United States
High angular resolution diffusion imaging (HARDI) has drawn considerable attention for its powerful directional measure on predicting fiber orientation at
the level of subvoxel dimension. HARDI may improve the accuracy of WM tractography, which leads to an important application of brain structural
connectivity. However, due to the higher diffusion weighting (DW) b-value and substantial number of DW directions, its long scan time is often the
obstacle for extensive clinical application. In this study, we investigate the feasibility of the new reconstruction method, highly constrained back projection
reconstruction, which may significantly reduce HARDI scan time.